Natural-gas liquefaction



H. DUMARS Feb. 18, 1930.

NATURAL GAS LI QUEFACTI ON Filed Sept. 8. 1922 w E o k INVEN-TOR VHORHC'E DUMB/PS ATTORNEY v Patented Feb. 18, 1 930 UNITED s A'rEsPArENr: OFFICE HORACE DUMABS, OF NEW SUFFOLK, NEW YORK, ASSIGNOR, BYDIRECT AND MESNE TASSIGNMENTS,'OF TWO-THIRDS 'IO BOWEN -DUMALRS POWERCORPORATION, OF N EW YORK, M cunrz, or NEW ORK, n. Y.

N. '21,. A- CORPORATION OF NEW YORK, AND ONE-THIRD TO HERMANN I.

NATURAL-GAS IlI'QUErAc'rron Application filed September a, 1922. SerialNo. 586,996.

itably used as a gas and under suitable conditions may be used in adouble or treble aspect, namely, by utilizing the refrigereither or bothrespects make such attempts ating effect when it has reached itsdestination and the liquid is allowed to expand and return tq agaseousstage, or partly in this manner and partly by using the gasifiedliquid under its. pressure created by gasifaction, in order to producepower.

6 In the research of many years and experience due to active work whenair was first "liquefied commercially, and with much knowledge of the,many difficulties and intricate questions involved in the liquefactionof different gases, the present invention has been the discovery of thepossibilities of utilizing all of the factors that are involved-in thecharacter of natural gas, as well as the condition under which such gasis won from the ground. I

It is known that others have endeavored to compress naturaLgas and in sodoinghave compressed the, gas, and by the increased pressure of thenatural gas, the constituents, hydrocarbons making up natural gas, havebeen changed and the changes have been such that their deleteriouscontent finds its way into the resultant liquid. This deleterious effectdue to the compressionof natural gas is of various aspects, includingthe dissociation toa more or less extent, of the qualities of the gas,but also creating someextremely explosive chemical compound. which incommercially impractical or abortive for any practical use or after useofthe gas, and more particularly preclude the possibilities of safetransport. The excessive pressure may in part, have the effect ofcracking on the same generalprinciples as are involved in the nowso-called cracking methods for thetreatment of natural oils. Y

My process aims toovercomeallofthe difficulties heretofore experiencedor contemplated by those skilled 1n the art,f or the pur-;-

pose of making-possible the economical lique faction of natural gasaudits transportation to market and to permit its economic utilization.a

I will now describe in detail a specific embodiment of my process whichinvolves the following:

' I provide in reasonably close proximity to the natural gas Wells,apparatus which in its simplest form'may comprise what is known in theart as a temperature interchanger. In certain localities enormoussupplies of natural gas are available at a rock pressure running overyears uniformly at approximately 1000 pounds, and with the casingconstruction used and the safety equipment of the wells such gas isavailable at casing-head at a pressure which I establish for use in myapparatus through suitable connections at a fairly uniform pressurewhich may be any point between 300 to 1000 pounds. Associated with thetemperature interchangcr I connect an expansion engine into which thenatural gas passes at a predetermined pressure. This expansion engineisso designed that clearance relation to the volume of the cylinderpermits the expansion of the gas from the predetermined establishedpressure to a predetermined pressure such as 60 pounds, which pressureis suflicient to carry away the natural gas into the piping at the plantand to the places of utilization locally whereit is required and ismoved by the natural pressure.

In the expansion engine the drop, for example, from 300 to 60 poundswould reduce the temperature to something like 130 degrees, but I do notaim to realize this full drop in temperature'because the first expansionengine is intended to serve the purpose as hereinafter shown, to rotatethe shaft actuating the piston in a second expansion engine. The exhaustfrom the first expansion engine passes through the heat interchangerthrough which there passes into a counter-current through an internaltube, a fresh quantum of natural gas moving-under the predeterminedcasing-head exit pressure of, say, 300 pounds, whichfresh quantum of gasis therefore reduced in temperature to something higher than the 130degrees, but it is still maintained under its 300 pounds'press ure untilits exit from this single interchanger, passing into a second expansionengine. This second expansion engine is made of greater volumethan -thefirst expansion engine and the clearance is proportioned so that the gasontering at approximately 130 degrees, willbe expanded to zeropressure,and with such expansion, having this second engine properly dimensioned,the expansion drops the temperature with the drop in pressure, to thepoint of liquefaction of natural gas which is approximately -263. Thedimensions are such it safely can be within the zone of liquid andsafely pass the critical pointof liquefaction. Having to deal only withthe as, which has previously been analyzed and o a reasonably constantand known quality at casinghead, there will be no other gases to liquefywithin the reasonable range of temperatures for which the apparatus isdesigned to reduce temperature in the second stage, thereby keeping outof the liquid any other liquefied admixtures that mingle with or changethe gharacter ofthe liquefied gas.

Between the casing-head and the first expansion engine there'aresuitable straining tanks for the purpose of drying and clarifying thenatural gas dependent upon the analysis of the gas at the particularcasing-head when the process is being operated. This includes theseparation of gasoline, or what is thought'desirable in order that itmay be.

eliminated as a factor in the liquefaction step and also be eliminatedfrom the gas delivered h at market from the liquid transported andexpanded for use for refrigeration, power and fuel.

It will be noted that the first expansion engine passes thenatural gaswithout any excessive change in temperature and with a regulated outletexhaust pressure, so ,that it may be utilized without any losswhatsoever, so that the first expansion step serves the purpose of whattoday are necessary expan- I sion valves required at the gas fields toreduce the pressure for commercial local use.

A diagrammatic illustration of one embodiment of my system is shown inthe accompanying drawing, in which: v

Natural gas at high pressure, such as direct from wellhead, flowsthrough the pipe 1, while a separate supply by a wellhead pressure flowsthrough the pipe 2, each of these leading to opposite ends of adouble-acting engine, as,for example, a Corliss engine comprising onecylinder 4, but in effect, for this purpose providing two cooperatingexpansion cylinder spaces or two effective expansion engines. The valves5 and 6 cooperate in the usual manner whereby with one closed, as 6,after the admission of the high pressure gas from the well, and valve 7opens, the gas previously admitted through 6,will expand and drive thepiston 9, expelling the previously expanded gas on the other side outof.

the interchanger 13. This gas having expanded, its resultant adiabaticcooling rethe-valve 7 through the conduit or pipe 12 to sults in gas ata much reduced temperature passing through the interchanger,diagrammatically illustrated at 13, and thereby cools thequantum of'gaspassing at high pressure from the well through pipe 1. The inter changermay be of any usual construction familiar to those in the art, as, for:example, indicated in Patents Nos. 749,040, January 5,

1904, or 1,074,103, September 30, 1913. This pre-cools the quantum ofgas passing through the supply pipe 1 at predetermined wellheadpressure, so that their further expansion after passing through valve 6,and driving piston 9, results in a further adiabatic cooling, so thatwhen the piston returns expelling the pre-cooled and further expandedgases out:

of valve 8, they pass into the trap 14 where the liquefied gases settleand are drawn off by the valve 17, and any surplu's'unliquefied gaspasses through the overflow 15 and is led into storage or to pipe line,with any suitable valve control to meet the particular conditions in anyone case; The engine used for expansion may have,asdiagrammaticallyindicated, a piston rod 10 with suitable crosshead,connecting-rod and crank driving a suitable pulley for transmission ofpower, and with flywheel and any usual parts desired for propertransmission or absorption of power and control.

By my utilization of the controlled pressure emanating from the naturalgas wells, I utilize a vast amount of natural energy which today goes to-waste absolute. The

utilization of this pressure by the control and interconnection of stepsin my apparatus, converts this energy at no cost whatsoever-beyond theinitial cost of the apparatus to serve the purpose of liquefying the gasto anextent of 50 per cent or less of the gas passing through theapparatus. The exact proper-- tion of the gas liquefied will depend uponthe efliciency of the apparatus with respect to insulation andefficiency of the engines and uniformity of operation and other factorswhich will be evident to those skilled in the art of manufacture ofapparatus.

In the entire process it will be seen that the progress is from higherto lower pressures and at no point is there any recompression, thereforeeliminating entirely any question of compressing with the deleteriouseffects that have heretofore been found, and, furthermore, eliminatingthe cost of compression 1 or recompression which compression hasheretofore been the underlying basis of the production of liquefiedgases.

Having produced the liquid natural gas without any compression'b'eyondthe natural condition at the well, and without any recompression, theresultant liquor does not have the prohibitive dangers'or changedqualities which have been found to preclude any commercial use ofcompressed natural gas, and therefore I provide suitable means oftransport, such as tank cars, which will carry the liquid and deliverthe same at market.

The transportation methods and the gasifica- ,tion with therefrigerating utilization at market, involve the physical and structuralapparatus which may vary materially and will not therefore bespecifically described in this particular application. a

It will be realized that modifications may be made, and under certainconditions similar results may be effected by variations in I theprocess and apparatus still containing the essential factors necessaryfor the results hereinbefore set forth. Under certain condi tions theequivalent of an expansion engine in one or both steps may be resortedto, but while many similar other essential conditions, a plurality ofinterchangers maybe used particularly when the expansion engines are notactuated in combination as hereinbefore' specifically set forth.

Essentially the process involves my discovery of the possibilities ofutilizing the now almost entirely Wasted pressure energy of natural gasat the wells, and making it perform in a practical andcommercial waywhat heretofore has been the prime and essential cost factor inliquefaction of gases.

\Vhile not confining myself to the specific process and apparatus abovedescribed, what I claim and desire to secure, by Letters Pattent is:

.The process of liquefying natural gas as delivered at two points fromthe well, comprising admitting a portion of the gas at well temperatureand pressure to anexpansion engine, thereby reducing the pressure andtemperature of the gas, controlling the temperature and pressure to keepsaid gas from liquefying in said expansion engine, passing the cooledgasfrom said expansion device into heat-interchanging relation with theother portion of gas at well temperature and pressure, and admittingsaid second portion of pre-cooled gas to a second expansion engine, sodesigned as to expansive capacity to liquefy at least a portion of said"as. n In testimony whereof, I have signed my name to this application,this 7th day of September, 1922.

HORACE DUMARS.

